Executive Summary
The water of concern is High Island Creek and its watershed. The High Island Creek Watershed is located in south central Minnesota, in the Lower Minnesota Watershed, which is a sub-basin of the Minnesota River Basin. The High Island Creek Watershed covers 153,222 acres in three counties, Sibley (66% area), McLeod (23%) and Renville (11%). The topography of the watershed is flat to gently rolling in the western 2/3rds, to steeply sloped in the eastern one-third. High Island Creek Watershed contains three cities, Arlington, New Auburn, and a portion of Stewart. Approximately 85% of the land use is agricultural. The water quality concerns of the High Island Creek Watershed are fecal coliform (FC) bacteria, total phosphorus (TP), total suspended solids (TSS) and nitrate+nitrite-n (NO2+NO3-N).

Fecal Coliform Bacteria is one of the most significant concerns in the watershed, as the entire High Island Creek is listed on the 303d list for fecal coliform bacteria. Levels of FC bacteria were frequently over the surface water standard of 200 organisms per 100 milliliters at all ten primary and secondary monitoring sites. Monitoring data and DNA fingerprinting by the University of Minnesota suggests that applied manure and noncompliant feedlots are the major sources of FC contamination in the High Island Creek Watershed.

Total Phosphorus levels are another significant concern in the watershed. The Lower Minnesota River Basin, of which High Island Creek Watershed is located in, is listed on the 305b list for dissolved oxygen (DO). Excessive TP levels, such as found at the outlet of High Island Creek contributes to the low DO levels in the Lower MN River Basin. Reductions in TP levels from High Island Creek is an important step in reaching the TMDL for DO in the Lower MN River basin. The majority of TP load at the outlet of High Island Creek is sediment bound in origin, from excessive soil erosion in the steeply sloped eastern portion of the watershed.

Total Suspended Solids concentrations at the outlet of High Island Creek ranked as one of the worst sites in the Minnesota River Basin for Flow Weighted Mean Concentration (FWMC), based from the State of the Minnesota River - 2001 Report. Monitoring data revealed the major source of TSS is from the highly sloped eastern portion of the watershed. This area represented only 26% of the watershed acres, but over 90% of the TSS load in 2001 and 2002 and monitoring seasons (April through September).

Nitrate+Nitrite-N is a significant concern, as monitoring data revealed high concentrations in several portions of High Island Creek Watershed. Monitoring data indicated High Island Creek to be a significant source of NO2+NO3-N to the Minnesota River, with FWMC ranking near the highest for all sites monitored in the Minnesota River Basin in 2001. Unlike TSS and TP, the majority of NO2+NO3+N load is attributed to the western portions of High Island Creek and its tributary Buffalo Creek.

For the complete High Island Creek Watershed Assessment Project, Diagnostic Report/Implementation Report